Definition

Noun: 1. A class of arthropods: Arachnida is a major class within the phylum Arthropoda. Its members are characterized by having four pairs of walking legs, a body typically divided into two main parts (the cephalothorax and the abdomen), and no antennae or wings. This class includes spiders, scorpions, ticks, mites, and harvestmen (daddy longlegs).

Usage Examples

• Noun:
  • Spiders and scorpions both belong to the class Arachnida.
  • The study of Arachnida is called arachnology.
  • Unlike insects, members of Arachnida have eight legs.

Advanced Usage

• In scientific taxonomy: The term is always capitalized ("Arachnida") when referring to the formal taxonomic class. It is used in biological classification to group related organisms.
  • The order Araneae falls under the class Arachnida.

Variants and Related Words

• Arachnid (n): A member of the class Arachnida; an individual creature such as a spider or tick.
  • A spider is an arachnid.
• Arachnological (adj): Relating to the study of arachnids.
• Arachnology (n): The scientific study of arachnids.

Synonyms

• Arachnids (when used as a collective plural noun for the creatures themselves).

Notes on Meaning

• The word "Arachnida" refers specifically to the scientific classification category. In everyday language, people typically use the common names (spider, scorpion) or the collective term "arachnids" to refer to these animals. The term "Arachnida" itself is primarily used in academic, scientific, or educational contexts.

Noun

1. a large class of arthropods including spiders and ticks and scorpions and daddy longlegs; have four pairs of walking legs and no wings